At the request of the Director, NICHD, we are preparing a review of current unresolved issues relating to the adverse health effects of cigarette smoking during pregnancy. This project involves a review of the literature of the subject which has appeared since the 1973 Surgeon General's Report on Smoking and Health. The reveiw covers lowered birth weight, perinatal mortality, spontaneous abortions, and the biochemical effects of smoking related to fetal development.